Airports are the absolute BEST places for writing music. you can get a beer, no distractions, quiet areas and lots of time to kill. Plus nobody cares if you're sat alone with a gameboy, unlike in pubs where it's just wierd.
I used to keep everything spaced apart on the main screen so it loops until changed. It was all a bit of a mess but parts like the chorus or bridges were always aligned. This kept the fingers busy on stage. Now i just write in song mode, with chains containing 4 phrases always... to give more freedom for doing other stuff, electribe/kaoss etc.. or pretending to hit buttons
Although the former method allowed me to mix songs from left to right DMG to keep a continuous sound going.